I spent two days last month flipping between two versions of a 40-page contract, trying to spot what the other party changed. Page by page. Manually. It was miserable, and I missed a clause they quietly deleted on page 31.
After that, I went looking for tools that actually compare PDF files and highlight the differences automatically. I tested about a dozen options, and here are the seven that worked well enough to recommend. Some are free, some have free tiers, and one is paid but worth mentioning because it’s what everyone asks about.
If you work with PDFs regularly, you probably already know about free PDF editors for making changes. But comparing two versions of the same document is a different problem, and most PDF editors don’t handle it. You need a dedicated comparison tool.
Quick Comparison Table
| Tool | Price | Platform | Max File Size (Free) | Comparison Type | Best For |
|---|---|---|---|---|---|
| Draftable Online | Free / $129/yr | Web | 10 MB | Text + visual | Quick side-by-side checks |
| PDF24 Tools | Free | Web + Desktop | No limit | Visual overlay | Catching layout changes |
| Diffchecker | Free / $9/mo | Web | 5 MB | Text-level | Pure text diffs |
| Adobe Acrobat Pro | $22.99/mo | Desktop + Web | N/A (paid) | Text + visual + fonts | Professional/legal work |
| PDF-XChange Editor | Free / $56 (Plus) | Windows | No limit | Text + annotations | Windows power users |
| Copyleaks | Free tier / $10.99/mo | Web | 2,500 words | AI text analysis | Checking for rewritten content |
| Google Docs Method | Free | Web | ~15 MB (Drive limit: 15 GB) | Text-level | No-install fallback |
1. Draftable Online – Best Free Option for Most People
Draftable is the tool I reach for first. Upload two PDFs, hit compare, and you get a side-by-side view with every change highlighted. Additions show up in green, deletions in red. You can click on any change to jump to the matching spot in the other document.
The free version handles files up to 10 MB with no signup required. I compared a 28-page PDF in about 4 seconds. It picks up text changes, moved paragraphs, and even formatting differences like font size changes.
What works well
- No account needed for basic comparisons
- Supports PDF, Word (.docx), and PowerPoint files
- Change summary panel shows total additions and deletions
- Results stay available for 30 minutes (free tier)
Limitations
- 10 MB file size cap on free tier
- Can’t compare scanned PDFs (image-based). You’d need to run OCR first
- No batch comparison
- Paid plan ($129/year) unlocks API access and larger files
For the kind of work most people need – checking if someone changed a contract, comparing report drafts, reviewing updated policies – Draftable handles it without friction.
2. PDF24 Tools – Best Free Option Without File Size Limits
PDF24 takes a different approach. Instead of showing text-level changes, it overlays the two PDFs on top of each other and highlights visual differences. Think of it like holding two sheets of paper up to a light.
This matters when you care about layout changes, not just text. If someone moved a logo, changed margins, swapped an image, or shifted a table – PDF24 catches it. Text-only comparison tools miss all of that.
What works well
- Completely free, no file size limit
- Visual overlay shows layout and image changes
- Desktop version available (Windows) for offline use
- Part of a larger PDF toolkit (merge, compress, convert)
Limitations
- Visual comparison can be noisy on documents with many small changes
- Doesn’t generate a text-level change log
- Overlay mode requires some interpretation – it’s not as obvious as red/green highlighting
I use PDF24 specifically when I suspect design or layout changes. For a contract where only text matters, Draftable is better. For a brochure or a presentation exported to PDF, PDF24 is the right call.
PDF24 also has solid PDF compression and other tools built in, so you get a lot of utility from one bookmark.
3. Diffchecker – Best for Pure Text Comparison
Diffchecker started as a plain-text diff tool and later added PDF support. The PDF comparison extracts text from both files and runs a line-by-line diff. If you’ve ever used a code diff tool, this will feel familiar.
The free tier gives you 3 comparisons per day with a 5 MB limit. That’s enough for occasional use. The results page shows text from both documents side by side, with additions, deletions, and modifications color-coded.
What works well
- Clean, developer-friendly interface
- Shows exact character-level changes within each line
- Also compares images, Excel files, and plain text
- Desktop app available ($9/month or $49 lifetime)
Limitations
- Free tier limited to 3 PDF comparisons per day
- 5 MB file limit (free)
- Strips formatting during extraction – you see the text, not the layout
- Scanned PDFs won’t work without OCR preprocessing
Diffchecker is my pick when I need character-level precision. The other tools highlight that something changed; Diffchecker shows exactly which words within a sentence were modified. For legal or technical documents where a single word matters, that level of detail is valuable.
4. Adobe Acrobat Pro – The Paid Standard
I know, this article is about free tools. But Acrobat Pro comes up in every PDF comparison conversation, so let me address it directly: it’s good, it’s thorough, and it costs $22.99/month.
The “Compare Files” feature in Acrobat Pro analyzes both text and visual elements. It generates a summary report showing every change, categorized by type (text, images, formatting, annotations). You can filter by change type and navigate through them one by one.
What works well
- Most thorough comparison available – catches everything including font changes and metadata
- Detailed summary report you can save or share
- Handles large, complex PDFs without performance issues
- Integrates with the rest of the Acrobat ecosystem
Limitations
- $22.99/month or $263.88/year – expensive for occasional use
- No free tier for comparison specifically
- Interface has a learning curve
- Desktop install required (about 1.2 GB)
If you compare PDFs daily for work – legal review, regulatory compliance, publishing – Acrobat Pro pays for itself. For everyone else, the free tools above cover 90% of use cases. You can always edit PDFs without Adobe too, comparison included.
5. PDF-XChange Editor – Best Free Desktop Option (Windows)
PDF-XChange Editor is a full-featured PDF editor for Windows that includes a document comparison tool in its free version. The comparison is text-based and shows differences inline with the document, so you see changes in context rather than in a separate panel.
The free version handles the basics. The Plus version ($56 one-time) adds more comparison options, including the ability to generate a comparison report and filter by change type.
What works well
- Free version includes basic comparison
- One-time purchase, not a subscription
- Works offline – no files uploaded to any server
- Handles large PDFs well (tested with 200+ page documents)
- Lightweight install (about 150 MB)
Limitations
- Windows only
- Free version adds a small watermark to saved files (comparison view itself is clean)
- Interface feels dated compared to web tools
- Plus version needed for advanced filtering and reporting
For Windows users who need to compare PDFs offline regularly, PDF-XChange is a solid choice. The one-time $56 price for the Plus version beats Adobe’s monthly subscription by a wide margin.
6. Copyleaks – Best for Catching Rewritten Content
Copyleaks is different from the other tools here. It uses AI to detect not just identical text changes but also paraphrased or rewritten content. If someone took a paragraph and rewrote it to say the same thing differently, Copyleaks flags it.
The free tier lets you compare up to 2,500 words. Paid plans start at $10.99/month for 25,000 words.
What works well
- Detects paraphrasing and rewording, not just direct changes
- Supports 30+ languages
- Side-by-side view with similarity percentage
- API available for integration
Limitations
- Free tier is very limited (2,500 words)
- Primarily designed for plagiarism detection, so the interface is geared toward that
- Doesn’t catch visual or layout changes
- Requires account creation
Honestly, most people don’t need this. But if you’re in academia, publishing, or legal work where someone might reword a section rather than just editing it, Copyleaks catches things the other tools miss entirely.
7. Google Docs Method – Free Workaround When You Have Nothing Else
This isn’t a dedicated tool, but it works in a pinch. Upload both PDFs to Google Drive, open each one with Google Docs (right-click > Open with > Google Docs), then use a text diff tool to compare the converted text.
Here’s the step-by-step:
- Upload both PDFs to Google Drive
- Right-click each file > Open with > Google Docs
- Copy all text from each converted document
- Paste both into Diffchecker’s free text comparison (or any text diff tool)
- Review the highlighted differences
What works well
- Completely free, no extra tools needed
- Works on any device with a browser
- Google’s PDF-to-text conversion is reasonably accurate
Limitations
- Manual process – takes 5-10 minutes
- Formatting gets stripped during conversion
- Tables and columns often get mangled
- Won’t work for image-heavy or scanned PDFs
I include this because sometimes you’re on a locked-down work computer where you can’t install anything and the web tools are blocked. Google Docs is almost always available, and this method works for simple text documents.
Which Tool Should You Pick?
Here’s how I think about it:
- Checking a contract or legal document? Draftable for quick checks, Acrobat Pro if you do this daily
- Comparing design files or formatted documents? PDF24 for visual overlay
- Need character-level precision? Diffchecker
- Working offline on Windows? PDF-XChange Editor
- Worried about paraphrased content? Copyleaks
- Nothing else available? Google Docs method
For most people reading this, start with Draftable. It’s free, fast, requires no signup, and handles the majority of comparison scenarios. If it doesn’t catch what you need, move to PDF24 for visual changes or Diffchecker for text precision.
And if you’re dealing with scanned PDFs, run them through OCR software first. None of these tools can compare text that’s actually an image.
Tips for Better PDF Comparisons
Before you compare
- Make sure both files are text-based PDFs, not scans. Open the PDF and try to select text – if you can’t, it’s a scan and needs OCR first
- Name your files clearly (contract_v1.pdf, contract_v2.pdf) so you don’t mix up which is which
- If the files are over 10 MB, compress them first – most free tools have size limits
During comparison
- Start with the summary/change count before diving into details. If there are 200+ changes, you might want to focus on specific sections
- Watch for moved text – some tools flag moved paragraphs as “deleted + added” rather than “moved,” which inflates the change count
- Check headers, footers, and page numbers separately. These often trigger false positives
After comparison
- Export or screenshot the comparison results before the session expires (Draftable’s free results last 30 minutes)
- For legal documents, always do a final manual read-through even after automated comparison. Tools can miss subtle changes in punctuation or spacing that change meaning
Frequently Asked Questions
Can I compare two PDF files for free without signing up?
Yes. Draftable Online and PDF24 Tools both let you compare PDFs without creating an account. Draftable handles files up to 10 MB with text-level comparison, while PDF24 has no file size limit but focuses on visual differences. Just upload your two files and get results in seconds.
How do I compare scanned PDF documents?
Scanned PDFs contain images of text, not actual text data, so comparison tools can’t read them directly. You need to convert them to searchable PDFs using OCR (Optical Character Recognition) software first. Free options include PDF24’s OCR tool and Google Docs’ built-in conversion. After OCR processing, any of the comparison tools in this guide will work.
What’s the difference between visual and text-based PDF comparison?
Text-based comparison (Draftable, Diffchecker) extracts the text from both PDFs and compares it word by word. It catches added, deleted, or modified text but may miss layout changes. Visual comparison (PDF24) overlays the two PDFs and highlights any pixel-level differences, catching layout shifts, image changes, and formatting differences that text comparison misses. Use text-based for contracts and documents; use visual for design files and formatted reports.
Is it safe to upload PDFs to online comparison tools?
Most reputable tools (Draftable, PDF24, Diffchecker) delete uploaded files within hours. Draftable states files are removed after 30 minutes on the free tier. However, if your PDFs contain sensitive information like financial data, personal records, or trade secrets, use an offline tool like PDF-XChange Editor instead. Your files never leave your computer with desktop software.
Can I compare more than two PDF files at once?
Most free tools only compare two files at a time. If you need to compare multiple versions (say, v1 vs v2 vs v3), you’ll need to run separate comparisons: v1 vs v2, then v2 vs v3. Adobe Acrobat Pro can handle this workflow more efficiently with its comparison history, but there’s no free tool that does true multi-file comparison in a single view.